In recent years, in a large scaled distributed processing network system, the most important agenda is availability. If the distributed processing network system cannot be operated for 24 hours, 365 days without stopping, it is difficult to use the distributed processing network system for a core corporate. Specifically, to increase the operability of the distributed processing network system, it is necessary to improve reliability of the distributed processing network system and high speed responsiveness of information processing.
Currently, in order to improve the reliability of the communication, distributed processing is performed in an application and most of network systems have a redundant configuration. However, the expansion of services that use the distributed processing network system causes dramatic increase of traffics. Further, increase in power consumption in a data center and a network system, which perform the distributed processing and have a redundant configuration, is a concern for future use. Therefore, to focus on the low power consumption, it is required to efficiently reduce an enlarged network while establishing the reliability and optimally rearrange a virtual server or a virtual switch. As a result, a failure analysis technology is required. As a related art of the failure analysis method, Patent Literature 1 or Patent Literature 2 discloses a technology that detects the status change using a network tomography.